Lubricant



Patented July 21, 1942 UNITED STATES. PATENT OFFICE 5,290,816 f LUBRICANT Elmer William Cooh'New York, N. Y., assignor to Tide Water Associated Oil Company, N. 1., a corporation of Delaware No Drawing. Application Bayonne,

January 2i, i941,

serum. 875,259

, This invention relates to lubricants intended for service in the lubrication of internal com-- bustion engines and to a novel type of inhibitor for incorporation with said lubricants. The invention more particularly is'concerned with lubricating or motor oils of mineral hydrocarbon origin which are normally corrosive toward bearing metal alloys of the character of cadmiumsilver, cadmium-nickel or copper-lead and has for-an important objective the inhibition or prevention of deterioration of such bearing metal in service by thecorrosive action of the lubricant thereon.

Engine bearings comprising or surfaced with cadmium-silver or like alloys now are frequently employed, particularly in engines to be used in heavy duty work, in lieu of the more usual Babbitt metal bearings in order to cope with the extreme service conditions of friction and temperature. These conditions are the consequences of modern developments in internal combustion engines making available high sustained speeds and requiringbearings formed'of metals or alloys having-greater resistance towear and further characterized by higher melting points necconditions existing duringbperation of the engine. Temperatures at the bearing surfaces during operation are or may be much higher in the case of engines requiring these new bearings than formerly was the case with engines in which Babbitt metalbearings gave satisfactory service. Experience with bearings of the character or type exemplified by cadmium-silver, cadmium-"nickel and copper-lead alloys has demonstrated, however, lthat their utility .is

- greatly impaired by an extreme, susceptibility to rapid deterioration by the corrosive action or eifect of many available lubricating oils. ,Particularly has this efiect been noted when the essary'to prolonged life under extreme thermal According to the invention it has now been found that the corrosive effect of lubricating oils upon bearing surfaces of the character referred to above may be avoided in novel and eflective manner by the addition to such oils of' relatively small proportional amounm of certain compounds containing sulfur and an amino group residue. More particularly according to the invention it has'been discovered that compounds; of=this class comprising, the reaction product of an aldehyde-amine and sulfur or' a suitable sulfur containing compound such, for example-as a polysulflde are very effective in inhibiting said corrosive action. Compounds of this class are believed to contain or be characterized by the presence of the nucleus ,The stated reaction products which will be termed herein sulfurized aldehyde amines aretherefore thought to conform with the general formula H 'R J NR' I s They may be produced from aldehyde amines derived from aldehydes vand amines of alkyl, aryl, a'ralkyl structure; including those of polycyclic structure. Thus, in the formula shownabove R may be alkyl, aryl or aralkyl' and R may be alkyl, aryl or aralkyl residues, the term aryl including polycyclic groupings such as, for example, the naphthyl radical.

It is therefore an important object of the present invention to inhibit or retard the-coroils are of the character generally regarded as superior lubricants by conventional criteria.

While the exact nature or cause of the stated corrosive action is not definitely known, it has been observed that motor oil derived from selective crudes predominantly paraflinic in origin, as well as'those oils from these or other crudes which have been improved by treatment with selective solvents, exhibit a marked tendency toward corrosiveness of the bearings in question although by other tokens the lubricant is of superior quality. It is possible that the high bearing surface temperatures existing under service conditions with the alloy bearings may be a factor in occasioning they observed delete-I rious effect of motor oils thereupon? No theory in explanation of the observed corrosive action or the prevention thereof as herein proposed according to the invention is intended to. be relied upon.

rated therewith proportion.

mium-nickel, copper-lead or like alloys by applying thereto a him of lubricant comprising mineral hydrocarbon oil having incorporated therewith a small but eflective proportion ofacome pound of the type disclosed herein. .This method provides prolonged life and consequent improved service/ of the stated alloys, particularly when operating \conditions such as high sustained ing surface temperatures. Ordinarily, the oil selected for' use in applying the lubricating method of the invention to its intended service will be of a character generally regarded as of superiorgrade and refining. It will be understood, however, that the invention,.contemplates no limitation in this respect and that the method of lubrication herein disclosed may be practiced in conjunction with mineral hydrocarbon lubricating oils taken as a broad class and regardless of origin. i

The stated sulfurized aldehyde amines may be readily prepared by reacting aldehydes with amines to form aldehyde amines, certain of the latter compounds being known as Shiff bases,

and subsequently reacting the aldehyde amines with sulfur or a suitable 'sulfur containing sub-' stance. Those aldehydes havinghigh numbers of carbon atoms are preferably employed. For

example, heptaldehyde when reacted with amines and the reaction products treated with sulfur or an equivalent thereof as hereinafter set forth has been found particularly satisfactory as a starting material. In cases where aliphatic amines are employed they maybe of straight chain or branched chain structure. Examples of amines which I have found particularly suitable are amylamine, aniline and the polycyclic amines such as naphthylamine. As representative comlpunds which are contemplated in the present invention there may be mentioned sulfurized heptaldehyde-n-amylamine, thio heptaldehyde'naphthylamine, sulfurized heptaldehyde aniline, thio benzylidine n-amylamine and sulfur'ized crctonal alpha naphthylamine. In general, the invention also includes as inhibitors for the stated purpose'derivatives and substitution products of the aforementioned sulfurized aldehyde amines which may be dissolved in mineral lubricating oils.

Effective prbportions of inhibitors according to the invention will vary somewhat for different conditions of service and as between different compoundg In the great majority of cases, however, a necessary quantity of inhibitor added to the motor oil will be very small, ordinarily less than 1% by weight and frequently less than 0.5% by weight. As indicated hereinafter, proportions of the order of 0.2% by weight have proved markedly effective in. achieving the objects of the invention. The stated percentages are "not intended in adimitative sense as obviously the inhibitor may be, and is intendedto be, employed in any corrosion inhibiting proportion.

Illustrative of the method of preparing the novel inhibitor compounds of the invention is the method of preparing sulfurized heptaldehyde aniline. This method comprises mixing molarproportions of aniline and heptaldehyde, the reaction. progressing under its own' exothermic heat'of reaction. During the reaction water separates and this water is removed for the most part by decanting. Ether and sodium sulfate are added to remove the remaining water.

The product is then filtered and the ether evaporated off in vacuo. The residue, which is heptaldehyde' aniline, is then heated with sulfur in molecular proportions and the reaction" product is allowed to cool. The resulting product, sulfurized heptaldehyde aniline, may then,

be dissolved in desired amounts in mineral speed under load occasion unusually high bearusing the appropriate aldehydes and amines as starting materials, and treating the aldehyde amine reactionproduct with sulfur or suitable includingat least one each of the several newer bearing metal alloys described (1. e., cadmiumsilver, cadmium-nickel and copper-lead) is supported in a chamber in which air may circulate and the bearing surfaces are exposed for a period of 22 hours to a stream of oil sprayed under pressure continuously upon the corrodible area. i

The oil is maintained at a temperature of approximately 335 F. and the spray is so directed as to disperse the oil over the surface of the bearing. Means are provided for recirculating the sprayed oil so that a given quantity is used for a given test, thus simulating service conditions in anengine. The measure of corrosion is taken as the loss in weight of the bearing during the test.

The test method described above is carried out in the familiar Underwood corrosion apparatus lubricating oil. Other inhibitor compounds of the invention may be prepared in like manner,

supplied by the Scientific Instrument Company of Detroit, Michigan, in accordance with General Motors specifications.

Results obtained utilizing the foregoing test for comparative evaluation of motor oils with and without an inhibitor according to the invention provide specific illustration of the value and inhibiting effectiveness of the stated inhibitor compounds. The oil used for the tests was an S. A. E. 20 motor oil comprising a blend of well refined paraffinic base stocks and having an A. P. I. gravity of 30.1, Saybolt viscosity at F. of about 300 seconds, Saybolt viscosity at 210 F. of about 54 seconds and fiash point of Erample To a portionof such an oil was added 0.2% by weight "of sulfurized heptaldehyde n-amylamine which had been prepared by reacting heptaldehyde and n-amylamine and treating the resultmg product with sulfur in the manner described hereinabove. During the runs cadmium-silver,

cadmium-nickel and copper-lead bearings all 'were present, and comparative losses in weight;

due to corrosion were determined for the respective bearings. The results obtained in the test of this lubricant composition and of the S. All.

20 oil described containing no added substance are shown in the following table:

Bearing loss in grams per square decimeter of beermg surface Bearing Oil+0.'.'% thioheptalhyde-namylamlnc Oil blank Cadmium-silver Cadmium-nickel No loss. Copper-lead D0.

bearings. Inspection of these comparative test data shows a complete suppression of corrosion when the inhibitor is used in the proportions of 0.2%. However, for many instances of normal automotive use it is likely that smaller percentages ofv inhibitor will suflice.

1. Composition comprising a major proportion of a mineral lubricating oil and a minor proportion of a sulfurized aldehyde amine.

2. Composition comprising a major proportion.

of a mineral lubricating oil and a minor proportion of a sulfurized hepialdehyde amine.

3. Composition comprising a major proportion of a mineral lubricating oil and a minor proportion of sulfurized heptaldehyde-alpha-naphthy1- amine.

4. Composition comprising a major proportion of a mineral lubricating oil and a minor proportion of sulfurized heptaldehyde-n-amylamine.

5. Composition comprising a major proportion of a mineral lubricating oil and 'a minor proportion of sulfurized heptaldehyde aniline.

6. Mineral oil composition comprising a hydrocarbon lubricating oil of a character normally tending to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys when continually applied to the surface thereof under service conditions and a sulfurized aldehyde amine in corrosion inhibiting proportions.

7. Mineral oil composition comprising a hydrocarbon lubricating oil of a character normally tending to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and 'copper-lead alloys when continually applied to the surface thereof under service conditions and corrosion inhibiting proportions of a compound having the general structure wherein R and R represent alkyl, aryl or aralkyl groups. I

8. Mineral oil composition comprising a hydrocarbon lubricating oil of a character normally tending to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium nickel and copper-lead alloys when continually applied to the surface thereof under service conditions and corrosion inhibiting proportions of a sulfurized compound which will inhibit said corrosion and which is produced by reacting an aldehyde amine with a sulfur-containing substance.

9. Mineral oil composition comprising a hydrocarbon lubricating oil of a character normally tending .to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys when continually applied tothe surface thereof under service conditions and corrosion inhibiting proportions of a sulfurized compound produced by reacting an aldehyde amine withasulf.

tion of a lubricating oil and a minor proportion of a compound having the general structure wherein R and R represent alkyl, aryl or aralkyl groups.

11. A mineral oil engine lubricant containing constituents tending to cause corrosion of bearing surfaces having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys when continuously applied thereto in use and an added sulfurized substance in corrosion inhibiting proportions, said substance being efiective to inhibit said corrosion and having been prepared by reacting an aldehyde amine with a sulfur-containing material. r

12. A mineral oil engine lubricant containing constituents tending to cause corrosion of bearing surfaces having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys when continuously applied thereto in use and an added substance effective to inhibit corrosion of said bearing surfaces, said substance containing the structural group 13. The method of lubricating bearings having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys, which consists in applying to the bearing surfaces lubricant comprising mineral hydrocarbon oil normally tending to corrode said surfaces and having incorporated therein corrosion inhibiting proportions of a sulfurized aldehyde amine.

14. The method described in claim 13 in which the sulfurized aldehyde aminev is a sulfurized alkylaldehyde alkylamine.

15. The method described in claim 13in which the sulfurized aldehyde amine is sulfurized heptaldehyde-n-amylamine.

16. The method described in claim 13 in which the sulfurized aldehyde amine is a sulfurized alkylaldehyde amine.

I 17. The method of lubricating bearings having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys, which consists in'applying to the bearing surfaces lubricant comprising mineral hydrocarbon oil normally tending to corrode said surfaces and having incorporated therein corrosion inhibiting proportions of a compound containing the structural group:

- CERTIFICATE OF CORRECTION. Patent No. 2,290,516. July 21, 191 2.

ELILER WILLIAM COOK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Pag first column, lines 55 and 55, for "thio" read sulfurized-; and second 001- umn, in the table, last column thereof, for "thiohptalhyde-n amylamine" read -sulfurized hepizaldehyde-n-amylaminee-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of September, D. l9lp2.

, Henry Van Arsdale, (Seal) v I Acting Commissioner of Patents. 

